Additive manufacturing technique for printing three-dimensional parts with printed receiving surfaces

ABSTRACT

A method for printing three-dimensional parts with an additive manufacturing system, comprising printing successive layers having increasing cross-sectional areas, and printing layers of a three-dimensional part onto the previously printed layers, where a last layer of the previously printed successive layers has a cross-sectional area that is at least as large as a footprint area of the three-dimensional part.

CROSS-REFERENCE TO RELATED APPLICATION(S)

Reference is also hereby made to co-filed U.S. patent application Ser.No. ______, entitled “Print Head Nozzle For Use With AdditiveManufacturing System” (attorney docket no. S697.12-0231).

Reference is also hereby made to co-filed U.S. patent application Ser.No. ______, entitled “Draw Control For Additive Manufacturing Systems”(attorney docket no. 5697.12-0232).

Reference is also hereby made to co-filed U.S. patent application Ser.No. ______, entitled “Additive Manufacturing System With ExtendedPrinting Volume, And Methods Of Use Thereof” (attorney docket no.S697.12-0233).

Reference is also hereby made to co-filed U.S. patent application Ser.No. ______, entitled “Method For Printing Three-Dimensional Parts WithAdditive Manufacturing Systems Using Scaffolds” (attorney docket no.S697.12-0234).

BACKGROUND

The present disclosure relates to additive manufacturing systems forbuilding three-dimensional (3D) parts with layer-based, additivemanufacturing techniques. In particular, the present disclosure relatesto additive manufacturing systems for printing large 3D parts, andmethods for printing 3D parts in the additive manufacturing systems.

Additive manufacturing systems are used to print or otherwise build 3Dparts from digital representations of the 3D parts (e.g., AMF and STLformat files) using one or more additive manufacturing techniques.Examples of commercially available additive manufacturing techniquesinclude extrusion-based techniques, jetting, selective laser sintering,powder/binder jetting, electron-beam melting, and stereolithographicprocesses. For each of these techniques, the digital representation ofthe 3D part is initially sliced into multiple horizontal layers. Foreach sliced layer, one or more tool paths are then generated, whichprovides instructions for the particular additive manufacturing systemto print the given layer.

For example, in an extrusion-based additive manufacturing system, a 3Dpart may be printed from a digital representation of the 3D part in alayer-by-layer manner by extruding a flowable part material. The partmaterial is extruded through an extrusion tip or nozzle carried by aprint head of the system, and is deposited as a sequence of roads on asubstrate in an x-y plane while the print head moves along the toolpaths. The extruded part material fuses to previously deposited partmaterial, and solidifies upon a drop in temperature. The position of theprint head relative to the substrate is then incremented along a z-axis(perpendicular to the x-y plane), and the process is then repeated toform a 3D part resembling the digital representation.

In fabricating 3D parts by depositing layers of a part material,supporting layers or structures are typically built underneathoverhanging portions or in cavities of 3D parts under construction,which are not supported by the part material itself. A support structuremay be built utilizing the same deposition techniques by which the partmaterial is deposited. The host computer generates additional geometryacting as a support structure for the overhanging or free-space segmentsof the 3D part being formed. Support material is then deposited from asecond nozzle pursuant to the generated geometry during the printingprocess. The support material adheres to the part material duringfabrication, and is removable from the completed 3D part when theprinting process is complete.

SUMMARY

An aspect of the present disclosure is directed to a method for printingthree-dimensional parts with an additive manufacturing system. Themethod includes printing successive layers along a printing axis onto afirst receiving surface of a print foundation, wherein the printedsuccessive layers have increasing cross-sectional areas parallel to abuild plane that is normal to the printing axis, where a last layer ofthe printed successive layers defines a second receiving surface. Themethod also includes printing layers of a three-dimensional part ontothe second receiving surface, wherein the last layer of the printedsuccessive layers has a first cross-sectional area parallel to the buildplane, where a first layer defines of the three-dimensional part has asecond cross-sectional area parallel to the build plane, and wherein thefirst cross-sectional area is at least as large as the secondcross-sectional area.

Another aspect of the present disclosure is directed to a method forprinting three-dimensional parts with an additive manufacturing system,which includes providing a first cross-sectional area of a receivingsurface parallel to a build plane, providing a footprint area of athree-dimensional part parallel to the build plane, and generating toolpaths for successive layers that increase in cross-sectional areasparallel to the build plane from the first cross-sectional area to atleast the footprint area of the three-dimensional part. The method alsoincludes printing the successive layers with the additive manufacturingsystem onto the receive surface based on the generated tool paths, andprinting a three-dimensional part onto the printed successive layers.

Another aspect of the present disclosure is directed to a method forprinting three-dimensional parts with an additive manufacturing system,which includes printing a scaffold along a printing axis with theadditive manufacturing system, where the printed scaffold comprises aplurality of successive wedge portions offset along the printing axis,and where each wedge portion has a receiving surface with across-sectional area parallel to a build plane that is normal to theprinting axis. The method also includes printing a three-dimensionalpart onto each printed receiving surface, such that eachthree-dimensional part is associated with one of the receiving surfaces,where each three-dimensional part has a cross-sectional area parallel tothe build plane that is less than or equal to the cross-sectional areaof its associated receiving surface.

DEFINITIONS

Unless otherwise specified, the following terms as used herein have themeanings provided below:

The terms “about” and “substantially” are used herein with respect tomeasurable values and ranges due to expected variations known to thoseskilled in the art (e.g., limitations and variabilities inmeasurements).

Directional orientations such as “above”, “below”, “top”, “bottom”, andthe like are made with reference to a direction along a printing axis ofa 3D part. In the embodiments in which the printing axis is a verticalz-axis, the layer-printing direction is the upward direction along thevertical z-axis. In these embodiments, the terms “above”, “below”,“top”, “bottom”, and the like are based on the vertical z-axis. However,in embodiments in which the layers of 3D parts are printed along adifferent axis, such as along a horizontal x-axis or y-axis, the terms“above”, “below”, “top”, “bottom”, and the like are relative to thegiven axis. Furthermore, in embodiments in which the printed layers areplanar, the printing axis is normal to the build plane of the layers.

The term “printing onto”, such as for “printing a 3D part onto a printfoundation” includes direct and indirect printings onto the printfoundation. A “direct printing” involves depositing a flowable materialdirectly onto the print foundation to form a layer that adheres to theprint foundation. In comparison, an “indirect printing” involvesdepositing a flowable material onto intermediate layers that aredirectly printed onto the receiving surface. As such, printing a 3D partonto a print foundation may include (i) a situation in which the 3D partis directly printed onto to the print foundation, (ii) a situation inwhich the 3D part is directly printed onto intermediate layer(s) (e.g.,of a support structure), where the intermediate layer(s) are directlyprinted onto the print foundation, and (iii) a combination of situations(i) and (ii).

The term “providing”, such as for “providing a chamber” and the like,when recited in the claims, is not intended to require any particulardelivery or receipt of the provided item. Rather, the term “providing”is merely used to recite items that will be referred to in subsequentelements of the claim(s), for purposes of clarity and ease ofreadability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side view of a 3D part being printed with a supportstructure and scaffold, illustrating a vertical printing axis.

FIG. 1B is a side view of a 3D part being printed with a supportstructure and scaffold, illustrating a horizontal printing axis.

FIG. 2 is a top view of a first example additive manufacturing system ofthe present disclosure having a platen and platen gantry for printing a3D part horizontally.

FIG. 3 is a side view of the first example system.

FIG. 4A is a perspective view of a 3D part, support structure, andscaffold printed on the platen.

FIG. 4B is an exploded perspective view of the 3D part, supportstructure, and scaffold printed on the platen.

FIG. 5 is a side view of the first example system, illustrating the 3Dpart being printed horizontally.

FIG. 6 is a top view of a second example additive manufacturing systemof the present disclosure having a platen starter piece for printing a3D part horizontally.

FIG. 7 is a side view of the second example system.

FIG. 8A is a perspective view of a 3D part, support structure, andscaffold printed on the platen starter piece.

FIG. 8B is an exploded perspective view of the 3D part, supportstructure, and scaffold printed on the platen starter piece.

FIG. 8C is a perspective view of a 3D part, support structure, andscaffold printed on the platen starter piece, illustrating analternative drive mechanism.

FIG. 9 is a side view of the second example system, illustrating the 3Dpart being printed horizontally.

FIG. 10 is a top view of a third example additive manufacturing systemof the present disclosure having a wedge starter piece for printing a 3Dpart horizontally.

FIG. 11 is a side view of the third example system.

FIG. 12 is an expanded side view of the wedge starter piece,illustrating a technique for printing a support structure.

FIG. 13A is a perspective view of a 3D part, support structure, andscaffold printed on the wedge starter piece.

FIG. 13B is an exploded perspective view of the 3D part, supportstructure, and scaffold printed on the wedge starter piece.

FIG. 14 is a side view of the third example system, illustrating the 3Dpart being printed horizontally.

FIG. 15 is a side view of a fourth example additive manufacturing systemof the present disclosure having a wedge starter piece for printing a 3Dpart vertically.

FIG. 16 is a side view of the fourth example system, illustrating the 3Dpart being printed vertically.

FIG. 17 is a side view of a fifth example additive manufacturing systemof the present disclosure having a multiple chambers for providingmultiple temperature zones.

FIG. 18A is a front view of a horizontally-printed, thin-walled 3D partwith a scaffold.

FIG. 18B is a front view of a multiple, horizontally-printed,thin-walled 3D parts with a scaffold, where the multiple 3D parts areprinted laterally adjacent to each other.

FIG. 18C is a front view of a multiple, horizontally-printed,thin-walled 3D parts with multiple scaffolds, where the multiple 3Dparts are printed adjacent to each other in a stacked arrangement.

FIG. 19 is a rear perspective view of a vertically-printed, thin-walled3D part with a scaffold.

FIGS. 20A and 20B are perspective views of multiple 3D parts, supportstructures, and a scaffold printed on a wedge starter piece,illustrating a scaffolding technique for printing multiple, successive3D parts.

FIG. 21 is a top-view photograph of an example airfoil part printedhorizontally with a support structure and scaffold.

FIG. 22 is a front-view photograph of an example thin-walled panelprinted vertically with a scaffold.

FIG. 23 is a rear-view photograph of the example thin-walled panelprinted vertically with the scaffold.

DETAILED DESCRIPTION

The present disclosure is directed to an additive manufacturing systemhaving an extended printing volume for printing long or tall 3D parts.The additive manufacturing system includes a heated chamber having aport that opens the chamber to ambient conditions outside of thechamber. The system also includes one or more print heads configured toprint a 3D part in a layer-by-layer manner onto a print foundation(e.g., a platen or other component having a receiving surface) in theheated chamber.

As the printed 3D part grows on the print foundation, the printfoundation may be indexed or otherwise moved through the port. Theprinted 3D part may continue to grow out of the port until a desiredlength or height is achieved. The use of the port expands the printablevolume along a printing axis of the system, allowing long or tall 3Dparts, such as airfoils, manifolds, fuselages, and the like to beprinted in a single printing operation. As such, the 3D parts may belarger than the dimensions of the additive manufacturing system.

As discussed further below, the additive manufacturing system may beconfigured to print 3D parts in a horizontal direction, a verticaldirection, or along other orientations (e.g., slopes relative to thehorizontal and vertical directions). In each of these embodiments, thelayers of a printed 3D part may be stabilized by one or more printed“scaffolds”, which brace the 3D part laterally relative to the printingaxis of the system to address forces parallel to the build plane. Thisis in comparison to a printed “support structure”, which supports abottom surface of the 3D part relative to the printing axis of thesystem to address forces that are normal to the build plane.

For example, FIG. 1A is a simplified front view of 3D part 10 beingprinted in a layer-by-layer manner from print head nozzle 12, where thelayers of the 3D part 10 grow along the vertical z-axis. As such, the“printing axis” in FIG. 1A is the vertical z-axis, and each layerextends parallel to a horizontal x-y build plane (y-axis not shown).

The layers of 3D part 10 are printed on layers of support structure 14,which are correspondingly disposed on platen 16. Support structure 14includes a first series of printed layers 14 a that support the bottomsurface 10 a of 3D part 10 along the printing axis (i.e., along thevertical z-axis), thereby address forces that are normal to the buildplane. Layers 14 a assist in adhering 3D part 10 to platen 16 or othersuitable print foundation, and for reducing the risk of having layers 14a curl, while also allowing 3D part 10 to be removed from platen 16without damaging 3D part 10. In addition, support structure 14 includesa second series of printed layers 14 b that support overhanging surface10 b of 3D part 10 along the printing axis. In each instance, the layersof support structure 14 (e.g., layers 14 a and 14 b) support the bottomsurfaces of 3D part 10 (e.g., bottom surfaces 10 a and 10 b) along theprinting axis, thereby further addressing forces that are normal to thebuild plane.

In comparison, layers of scaffolds 18 a and 18 b are printed at laterallocations relative to 3D part 10 and are not used to support bottomsurfaces 10 a and 10 b. Rather, scaffolds 18 a and 18 b, illustrated astubular scaffolds extending along the z-axis, are printed to brace thelateral sides of 3D part 10 to function as buttresses to address forcesparallel to the build plane. For example, in some instances, such aswhen 3D part 10 is tall and narrow, the adhesion between layers 14 a and3D part 10 may not be sufficient to prevent the top-most layers of 3Dpart 10 from wobbling during the printing operation. The wobbling of 3Dpart 10 can reduce the registration between print head nozzle 12 and 3Dpart 10, potentially resulting in reduced printing accuracies. Scaffolds18 a and 18 b, however, provide a suitable mechanism to brace 3D part 10at one or more lateral locations relative to the printing axis (i.e.,the vertical z-axis), to stabilize 3D part 10 against wobbling.

Alternatively, FIG. 1B shows 3D part 20 being printed in alayer-by-layer manner from print head nozzle 22, where the layers of the3D part 20 grow horizontally along the z-axis. As such, the “printingaxis” in FIG. 1B is a horizontal z-axis axis, and each layer extendsparallel to a vertical x-y build plane (y-axis not shown).

In this situation, the layers of 3D part 20 are printed on layers ofsupport structure 24, which are correspondingly disposed on platen 26.Support structure 24 includes a first series of printed layers 24 a thatsupport the bottom surface 20 a of 3D part 20 along the printing axis(i.e., along the horizontal z-axis), and a second series of printedlayers 14 b that support overhanging surface 20 b of 3D part 20 alongthe printing axis. In each instance, the layers of support structure 24(e.g., layers 24 a and 24 b) support the bottom surfaces of 3D part 20(e.g., bottom surfaces 20 a and 20 b) along the printing axis to addressforces that are normal to the build plane.

In comparison, layers of scaffold 28 are printed at lateral locationsrelative to the layers of 3D part 20 and are not used to support bottomsurfaces 20 a and 20 b. Rather, scaffold 28 is printed to brace thelateral side of 3D part 20 relative to the printing axis, which is thevertical bottom side of 3D part 20 in the view shown in FIG. 1B. In thishorizontal situation, scaffold 28 braces 3D part 20, preventing 3D part20 from sagging in a direction parallel to the build plane under gravityduring the printing operation.

For example, in some instances, such as when 3D part 20 is long andnarrow, the cantilevered adhesion between layers 24 a and 3D part 20 maynot be sufficient to prevent the remote-most layers of 3D part 20 fromsagging under gravity during the printing operation. As such, scaffold28 provides a suitable mechanism to brace 3D part 20 at one or morelateral locations relative to the printing axis (i.e., the horizontalz-axis), reducing the risk of sagging. Scaffold 28 itself can then reston and slide along an underlying surface 29 in the y-z plane.

For ease of discussion, the z-axis is used herein when referring to theprinting axis regardless of the printing orientation. For a verticalprinting operation, such as shown in FIG. 1A, the printing z-axis is thea vertical axis, and each layer of the 3D part, support structure, andscaffold extend along the horizontal x-y build plane. Alternatively, fora horizontal printing operation, such as shown in FIG. 1B, the printingz-axis is a horizontal axis, and each layer of the 3D part, supportstructure, and scaffold extend along the vertical x-y build plane. Infurther alternative embodiments, the layers of 3D parts, supportstructures, and scaffolds may be grown along any suitable axis.

Additionally, while FIGS. 1A and 1B illustrate flat build planes (i.e.,each layer is planar), in further alternative embodiments, the layers ofthe 3D parts, support structures, and/or scaffolds may be non-planar.For example, the layers of a given 3D part may each exhibit gentlecurvatures from a flat build plane. In these embodiments, the buildplane may be determined as an average plane of the curvatures. Unlessexpressly stated otherwise, the term “build plane” is not intended to belimited to a flat plane.

As further discussed below, in some embodiments, the receiving surfaceson which the 3D parts, support structures, and/or scaffolds are printedon may have cross-sectional areas in the build plane that are smallerthan the footprint areas of the 3D parts, support structures, and/orscaffolds. For example, the receiving surface of a print foundation mayhave a cross-sectional area that is smaller than the footprint areas ofan intended 3D part. In this situation, layers of a support structureand/or scaffold may be printed with increasing cross-sectional areasuntil they at least encompass the footprint areas of the intended 3Dpart. This allows small print foundations to be used with the additivemanufacturing systems of the present disclosure. Furthermore, thisallows multiple, successive 3D parts to be printed with scaffolds thatfunction as receiving surfaces.

Horizontal Printing

FIGS. 2-14 illustrate example additive manufacturing systems of thepresent disclosure having extended printing volumes for printing long 3Dparts horizontally, such as discussed above for 3D part 20 (shown inFIG. 1B). FIGS. 2-5 illustrate system 30, which is a first exampleadditive manufacturing system for printing or otherwise building 3Dparts, support structures, and/or scaffolds horizontally using alayer-based, additive manufacturing technique. Suitable systems forsystem 30 include extrusion-based additive manufacturing systemsdeveloped by Stratasys, Inc., Eden Prairie, Minn. under the trademarks“FDM” and “FUSED DEPOSITION MODELING”, which are oriented such that theprinting z-axis is a horizontal axis.

As shown in FIG. 2, system 30 may rest on a table or other suitablesurface 32, and includes chamber 34, platen 36, platen gantry 38, printhead 40, head gantry 42, and consumable assemblies 44 and 46. Chamber 34is an enclosed environment having chamber walls 48, and initiallycontains platen 36 for printing 3D parts (e.g., 3D part 50), supportstructures (e.g., support structure 52), and/or scaffolds (e.g.,scaffold 54, shown in FIGS. 3-5).

In the shown embodiment, chamber 34 includes heating mechanism 56, whichmay be any suitable mechanism configured to heat chamber 34, such as oneor more heaters and air circulators to blow heated air throughoutchamber 34. Heating mechanism 56 may heat and maintain chamber 34, atleast in the vicinity of print head 40, at one or more temperatures thatare in a window between the solidification temperature and the creeprelaxation temperature of the part material and/or the support material.This reduces the rate at which the part and support materials solidifyafter being extruded and deposited (e.g., to reduce distortions andcurling), where the creep relaxation temperature of a material isproportional to its glass transition temperature. Examples of suitabletechniques for determining the creep relaxation temperatures of the partand support materials are disclosed in Batchelder et al., U.S. Pat. No.5,866,058.

Chamber walls 48 maybe any suitable barrier to reduce the loss of theheated air from the build environment within chamber 34, and may alsothermally insulate chamber 34. As shown, chamber walls 48 include port58 extending laterally therethrough to open chamber 34 to ambientconditions outside of system 30. Accordingly, system 30 exhibits athermal gradient at port 58, with one or more elevated temperatureswithin chamber 34 that drop to the ambient temperature outside ofchamber 34 (e.g., room temperature, about 25° C.).

In some embodiments, system 30 may be configured to actively reduce theheat loss through port 58, such as with an air curtain, therebyimproving energy conservation. Furthermore, system 30 may also includeone or more permeable barriers at port 58, such as insulating curtainstrips, a cloth or flexible lining, bristles, and the like, whichrestrict air flow out of port 58, while allowing platen 36 to passtherethrough.

Platen 36 is a print foundation having receiving surface 36 a, where 3Dpart 50, support structure 52, and scaffold 54 are printed horizontallyin a layer-by-layer manner onto receiving surface 36 a. In someembodiments, platen 36 may also include a flexible polymeric film orliner, which may function as receiving surface 36 a. Platen 36 issupported by platen gantry 38, which is a gantry-based drive mechanismconfigured to index or otherwise move platen 36 along the printingz-axis. Platen gantry 38 includes platen mount 60, guide rails 62, screw64, screw drive 66, and motor 68.

Platen mount 60 is a rigid structure that retains platen 36 such thatreceiving surface 36 a is held parallel to the x-y plane. Platen mount60 is slidably coupled to guide rails 62, which function as linearbearings to guide platen mount 60 along the z-axis, and to limit themovement of platen 36 to directions along the z-axis (i.e., restrictsplaten 36 from moving in the x-y plane). Screw 64 has a first endcoupled to platen mount 60 and a second portion engaged with screw drive66. Screw drive 66 is configured to rotate and draw screw 64, based onrotational power from motor 68, to index platen 36 along the z-axis.

In the shown example, print head 40 is a dual-tip extrusion headconfigured to receive consumable filaments or other materials fromconsumable assemblies 44 and 46 (e.g., via guide tubes 70 and 72) forprinting 3D part 50, support structure 52, and scaffold 54 ontoreceiving surface 36 a of platen 36. Examples of suitable devices forprint head 40 include those disclosed in Crump et al., U.S. Pat. No.5,503,785; Swanson et al., U.S. Pat. No. 6,004,124; LaBossiere, et al.,U.S. Pat. Nos. 7,384,255 and 7,604,470; Leavitt, U.S. Pat. No.7,625,200; Batchelder et al., U.S. Pat. No. 7,896,209; and Comb et al.,U.S. Pat. No. 8,153,182.

In additional embodiments, in which print head 40 is an interchangeable,single-nozzle print head, examples of suitable devices for each printhead 40, and the connections between print head 40 and head gantry 42include those disclosed in Swanson et al., U.S. Patent ApplicationPublication No. 2012/0164256.

Print head 40 is supported by head gantry 42, which is a gantry assemblyconfigured to move print head 40 in (or substantially in) the x-y planeparallel to platen 36. For example, head gantry 42 may include y-axisrails 74, x-axis rails 76, and bearing sleeves 78. Print head 40 isslidably coupled to y-axis rails 74 to move along the horizontal y-axis(e.g., via one or more motor-driven belts and/or screws, not shown).Y-axis rails 74 are secured to bearing sleeves 78, which themselves areslidably coupled to x-axis rails 76, allowing print head 40 to also movealong the vertical x-axis, or in any direction in the x-y plane (e.g.,via the motor-driven belt(s), not shown). While the additivemanufacturing systems discussed herein are illustrated as printing in aCartesian coordinate system, the systems may alternatively operate in avariety of different coordinate systems. For example, head gantry 42 maymove print head 40 in a polar coordinate system, providing a cylindricalcoordinate system for system 30.

Suitable devices for consumable assemblies 44 and 46 include thosedisclosed in Swanson et al., U.S. Pat. No. 6,923,634; Comb et al., U.S.Pat. No. 7,122,246; Taatjes et al, U.S. Pat. Nos. 7,938,351 and7,938,356; Swanson, U.S. Patent Application Publication No.2010/0283172; and Mannella et al., U.S. patent application Ser. Nos.13/334,910 and 13/334,921.

Suitable materials and filaments for use with print head 40 includethose disclosed and listed in Crump et al., U.S. Pat. No. 5,503,785;Lombardi et al., U.S. Pat. Nos. 6,070,107 and 6,228,923; Priedeman etal., U.S. Pat. No. 6,790,403; Comb et al., U.S. Pat. No. 7,122,246;Batchelder, U.S. Patent Application Publication Nos. 2009/0263582,2011/0076496, 2011/0076495, 2011/0117268, 2011/0121476, and2011/0233804; and Hopkins et al., U.S. Patent Application PublicationNo. 2010/0096072. Examples of suitable average diameters for thefilaments range from about 1.02 millimeters (about 0.040 inches) toabout 3.0 millimeters (about 0.120 inches).

System 30 also includes controller 80, which is one or more controlcircuits configured to monitor and operate the components of system 30.For example, one or more of the control functions performed bycontroller 80 can be implemented in hardware, software, firmware, andthe like, or a combination thereof. Controller 80 may communicate overcommunication line 82 with chamber 34 (e.g., heating mechanism 56),print head 40, motor 68, and various sensors, calibration devices,display devices, and/or user input devices.

In some embodiments, controller 80 may also communicate with one or moreof platen 36, platen gantry 38, head gantry 42, and any other suitablecomponent of system 30. While illustrated as a single signal line,communication line 82 may include one or more electrical, optical,and/or wireless signal lines, allowing controller 80 to communicate withvarious components of system 30. Furthermore, while illustrated outsideof system 30, controller 80 and communication line 82 are desirablyinternal components to system 30.

System 30 and/or controller 80 may also communicate with computer 84,which is one or more computer-based systems that communicates withsystem 30 and/or controller 80, and may be separate from system 30, oralternatively may be an internal component of system 30. Computer 84includes computer-based hardware, such as data storage devices,processors, memory modules and the like for generating and storing toolpath and related printing instructions. Computer 84 may transmit theseinstructions to system 30 (e.g., to controller 80) to perform printingoperations.

During operation, controller 80 may direct print head 40 to selectivelydraw successive segments of the part and support material filaments fromconsumable assemblies 44 and 46 (via guide tubes 70 and 72). Print head40 thermally melts the successive segments of the received filamentssuch that they become molten flowable materials. The molten flowablematerials are then extruded and deposited from print head 40, along theprinting z-axis axis, onto receiving surface 36 a for printing 3D part50 (from the part material), support structure 52 (from the supportmaterial), and scaffold 54 (from the part and/or support materials).

Print head 40 may initially print one or more layers of supportstructure 52 onto receiving surface 36 a to provide an adhesive base forthe subsequent printing. This maintains good adhesion between the layersof 3D part 50 and platen 36, and reduces or eliminates any tolerance toflatness between receiving surface 36 a of platen 36 and the x-y plane.After each layer is printed, controller 80 may direct platen gantry 38to index platen 36 along the z-axis in the direction of arrow 86 by asingle layer increment.

After support structure 52 is initially printed, print head 40 may thenprint layers of 3D part 50 and scaffold 54, and optionally anyadditional layers of support structure 52. As discussed above, thelayers of support structure 52 are intended to support the bottomsurfaces of 3D part 50 along the printing z-axis against curl forces,and the layers of scaffold 54 are intended to brace 3D part 50 againstgravity along the vertical x-axis.

As shown in FIG. 3, guide rails 62 are illustrated with cross hatchingand head gantry 42 is omitted for ease of viewability. As the printed 3Dpart 50 and scaffold 54 grow along the z-axis, the indexing of platen 36in the direction of arrow 86 moves platen 36 through chamber 34 towardsport 58. Port 58 desirably has dimensions that allow platen 36 to passthrough without contacting chamber walls 48. In particular, port 58 isdesirably parallel (or substantially parallel) to platen 36 (i.e., bothextend in the x-y plane), with dimensions that are slightly larger thanthe cross-sectional area of platen 36. This allows platen 36 (and thegrowing 3D part 50 and scaffold 54) to pass through port 58 withoutinterference, while also desirably reducing thermal loss through port58.

As the printed layers of 3D part 50, support structure 52, and scaffold54 move in the direction of arrow 86 through chamber 34 toward port 58,the temperature of chamber 34 gradually cools them down from theirrespective extrusion temperatures to the temperature in chamber 34. Asmentioned above, this reduces the risk of distortions and curling.Gantry assembly 38 desirably indexes platen 36 at a rate that is slowenough such that the printed layers cool down to the temperature(s) ofchamber 34, and reside in chamber 34 for a duration that is sufficientto substantially relieve cooling stresses, prior to reaching port 58.This allows the printed layers to be relaxed enough such that when theyreach the temperature gradient at port 58, the temperature drop at thetemperature gradient does not cause any substantial distortions orcurling.

FIGS. 4A and 4B illustrate 3D part 50, support structure 52, scaffold54, and platen 36 during the printing operation. 3D part 50 includesinterior structure 50 a and exterior surfaces 50 b, where interior frame50 a functions in the same manner as scaffold 54 for laterally bracingthe exterior surfaces 50 b of 3D part 50. In alternative embodiments,depending on the geometry of 3D part 50, interior structure 50 a may beomitted or may be printed from a support material that can besubsequently removed from 3D part 50 (e.g., a soluble support material).In embodiments in which interior structure 50 a is printed from asoluble support material, interior frame 50 a is desirably porous and/orsparse to increase the flow of a dissolving fluid (e.g., an alkalineaqueous solution) through the interior region of 3D part 50. This canincrease the dissolution rate of interior structure 50 a.

In the shown example, scaffold 54 includes ribbon portion 88 andconveyor base 90. Further details of this ribbon-base arrangement forscaffold 54 are discussed below. Briefly, ribbon portion 88 is connectedto exterior surface 50 b of 3D part 50 with small contact points tobrace 3D part 50 against sagging due to gravity. The small contactpoints allows ribbon portion 88 to be readily broken apart or otherwiseremoved from 3D part 50 after the printing operation is completed.Conveyor base 90 is a planar sheet that supports ribbon portion 88,providing a smooth surface that can rest on and slide over guide rails62 as platen 36 is indexed along the z-axis.

As further shown in FIGS. 4A and 4B, support structure 30 is desirablyprinted on receiving surface 36 a to at least encompass the footprintarea of 3D part 50 and scaffold 54 (i.e., the cross-sectional area of 3Dpart 50 and scaffold 54 in the x-y plane). In the shown example, supportstructure 30 only covers about the bottom 40% of platen 36. However, for3D parts and scaffolds having larger geometries in the x-y plane, theentire surface of platen 36 may be used, allowing 3D parts havingcross-sectional areas up to about the cross-sectional area of platen 36to be printed. Furthermore, the lengths of the 3D parts are limited onlyby the length of platen gantry 38. Thus, system 30 is suitable forprinting long 3D parts, having a variety of different cross-sectionalgeometries, such as airfoils, manifolds, fuselages, and the like.

As shown in FIG. 4B, platen 36 includes base indentation 91, which 91 isconfigured to align with the top surface of guide rails 62. Thisarrangement allows support structure 52 and conveyor base 90 of scaffold54 to be printed flush against indentation 91. This allows supportstructure 52 and scaffold 54 to rest on and slide across the top surfaceof guide rails 62 while platen 36 is indexed in the direction of arrow86.

As shown in FIG. 5, as platen gantry 38 continues to index platen 36 inthe direction of arrow 86, the successive layers of 3D part 50 andscaffold 54 pass through the thermal gradient at port 58 and moveoutside of chamber 34. As discussed above, the printed layers desirablycool down to the temperature(s) of chamber 34 prior to reaching port 58to reduce the risk of distortions and curling. Upon passing through port58, the printed layers may then cool down to the ambient temperatureoutside of chamber 34 (e.g., room temperature).

The printing operation may continue until the last layer of 3D part 50is printed and/or when platen 36 is fully indexed to the end of platengantry 38. As can appreciated, allowing platen 36 to move out of chamber34 increases the lengths of 3D parts that may be printed by system 30compared to additive manufacturing systems having enclosed chambers.

After the printing operation is completed, the printed 3D part 50,support structure 52, scaffold 54, and platen 36 may be removed fromsystem 30 (e.g., by disengaging platen 36 from platen gantry 38). Platen36 may then be removed from support structure 30, and support structure30 may be removed from 3D part 50 and scaffold 54 (e.g., by dissolvingsupport structure 30). Scaffold 54 may then be broken apart from orotherwise removed from 3D part 50.

While system 30 is particularly suitable for printing 3D parts that arelong along the z-axis (e.g., 3D part 50), system 30 may also print 3Dparts that are shorter along the z-axis. In instances where 3D part 50is short along the z-axis, such that the adhesiveness of supportstructure 52 is sufficient to support the 3D part in a cantileveredmanner without substantial sagging, scaffold 54 may be omitted. However,as can be appreciated, as the length of a 3D part grows along thez-axis, support structure 52 alone is not sufficient to preventremotely-printed layers of the 3D part from sagging under gravity. Inthis situation, one or more scaffolds (e.g., scaffold 54) may be printedalong with the 3D part to laterally brace the 3D part.

FIGS. 6-9 show system 230, which is a second example additivemanufacturing system having a platen starter piece and associated drivemechanism. As shown in FIG. 6, system 230 may operate in a similarmanner to system 30 (shown in FIGS. 2-5), where the reference numbersfor the respective features are increased by “200”. In this embodiment,platen 36 and platen gantry 38 of system 30 are replaced with a platenstarter piece 292 and drive mechanism 294.

Starter piece 292 is a removable print foundation having platen portion296, platform portion 298, and reinforcing arms 300 (best shown in FIG.8B). Platen portion 296 includes receiving surface 296 a for receivingthe printed support structure 252 in the same manner as receivingsurface 36 a of platen 36. Platform portion 298 includes edge segments302 and central segment 304, where edge segments 302 are offset acrossfrom each other along the y-axis. Platen portion 296 is integrallyformed with or otherwise connected to platform portion 298 at centralsegment 304, and does not extend laterally to edge segments 302. Assuch, platen portion 296 extends parallel to the x-y plane, and at aright angle to platform portion 298, which extends in the y-z plane.Reinforcing arms 300 are optional components that structurally reinforceplaten portion 296.

Starter piece 292 may be fabricated from one or more polymeric and/ormetallic materials. For example, starter piece 292 may be molded (e.g.,injection molded) or printed with an additive manufacturing system froma polymeric material to provide a rigid piece capable of supporting theprinted layers of 3D part 250, support structure 252, and scaffold 254.In an alternative embodiment, platform portion 298 may be a web-basedfilm with platen portion 296 secured thereon.

As shown in FIGS. 6 and 7, drive mechanism 294 is a wheel-based drivemechanism that includes two pairs of drive wheels 306, guide rails 308,and motor 310, where, in FIG. 7, guide rails 308 are illustrated withcross hatching (and head gantry 242 is omitted) for ease of viewability.Prior to the printing operation, platform portion 298 of starter piece292 may be inserted between the pairs of drive wheels 306. Platformportion 298 may also include one or more alignment tabs 312 (best shownin FIG. 8B) to align and slidably couple starter piece 292 to guiderails 308.

Guide rails 308 function as linear bearings along the horizontal z-axisin a similar manner to guide rails 62 (shown in FIGS. 2, 3, and 5).However, guide rails 308 may be considerably shorter in length comparedto guide rails 62, thereby reducing the size of system 10 on table 232.For example, guide rails 308 may be retained entirely within chamber234.

During operation, print head 240 initially prints one or more layers ofsupport structure 252 onto receiving surface 296 a to provide anadhesive base for the subsequent printing. This maintains good adhesionbetween the layers of 3D part 250 and receiving surface 296 a. However,as best shown in FIGS. 8A and 8B, the layers of support structure 252also include edge segments 314 corresponding to edge segments 302 ofstarter piece 292, and alignment tabs 316 (shown in FIG. 8B)corresponding to alignment tabs 312 of starter piece 292.

After each layer of support structure 252 is printed, drive mechanism294 may index starter piece 292 along the z-axis in the direction ofarrow 286 by a single layer increment. In particular, as shown in FIG.8A, each pair of drive wheels 306 may engage the opposing surfaces ofone of the edge segments 302. Drive wheels 306 are operated by motor310, which rotates drive wheels 306 to index starter piece 292 along thez-axis in the direction of arrow 286.

In alternative embodiments, drive mechanism 294 may be replaced with avariety of different drive mechanisms for engage with and moving starterpiece 292, support structure 252, and scaffold 254 in the same manner.For example, drive wheels 306 may be replaced with cogs, texturedwheels, spiked wheels, textured and/or tacky conveyor belts, and thelike to engage one side of each edge segment 302, both sides of eachedge segment 302, or combinations thereof.

After support structure 252 is printed, print head 240 may then printlayers of 3D part 250 and scaffold 254, and optionally any additionallayers of support structure 252. As further shown in FIGS. 8A and 8B,conveyor base 288 of scaffold 254 is printed to include edge segments318 corresponding to edge segments 302 and 314, and alignment tabs 320corresponding to alignment tabs 312 and 316. In alternative embodiments,alignment tabs 312, 316, and/or 320 may be omitted. In theseembodiments, system 230 may include other suitable features (e.g.,alignment pins) to maintain registration in the x-y plane.

As drive wheels 306 continue to index starter piece 292 in the directionof arrow 286, alignment tabs 316 of support structure 252 and alignmenttabs 320 of scaffold 254 eventually reach and slidably couple with guiderails 308 to maintain proper registration in the x-y plane. Furthermore,as illustrated by arrow 322 in FIG. 8A, drive wheels 306 eventually passedge segments 302 of starter piece 292, and engage edge segments 314 and318 to continue to index support structure 250 and scaffold 254 in thedirection of arrow 286. In some embodiments, system 230 may include oneor more sensors (not shown) to provide feedback to controller 280,thereby maintaining proper indexing of scaffold 250. For example, system230 may include one or more optical sensors to measure displacement ofscaffold 250 along the z-axis, which may transmit signals to controller280 to provide accurate an indexing of scaffold 250.

As can be appreciated, because drive wheels 306 engage scaffold 254 atboth sides of edge segment 318 of scaffold 254, the opposing drivewheels 306 may need to be adjusted along the y-axis to compensate forthe dimensions of 3D part 250. For instance, if 3D part 250 is very widealong the y-axis, the opposing pairs of drive wheels 306 may need to beseparated further apart along the y-axis (as illustrated by separationlines 321 in FIG. 8A) to accommodate the wider support structure 252 andscaffold 254. Alternatively, if 3D part 250 is very narrow along they-axis, the opposing pairs of drive wheels 306 may need to be movedcloser together along the y-axis to reduce the widths of supportstructure 252 and scaffold 254. This reduces the needed sizes of supportstructure 252 and scaffold 254. However, in one embodiment, drive wheels306 may be maintained at a separation distance along the y-axis thataccommodates the widest dimensions that can be printed by system 230. Inthis embodiment, support structure 252 and scaffold 254 may be printedwith widths that reach drive wheels 306.

Alternatively, as shown in FIG. 8C, system 230 may include analternative drive mechanism, such as drive mechanism 294 a, that engagesonly the bottom surfaces of starter piece 292, support structure 252,and scaffold 254. As shown, drive mechanism 294 a includes rollers 306 aand drive belt 306 b, where drive belt 306 b engages the bottom surfacesof starter piece 292, support structure 252, and scaffold 254. Thebottom surface engagement allows drive mechanism 294 a to be usedregardless of the dimensions of 3D part 250, support structure 52, andscaffold 254.

Drive belt 306 b may engage with starter piece 292, support structure252, and scaffold 254 with a variety of features, such a textured and/ortacky belt surface. This allows drive belt 306 b to frictionally,mechanically, and/or adhesively grip the bottom surfaces of starterpiece 292, support structure 252, and scaffold 254 to index or otherwisemove them in the direction of arrow 286. The engagement between drivebelt 306 b and starter piece 292, support structure 252, and scaffold254 may be based on the weights of starter piece 292, support structure252, and scaffold 254, which hold them against drive belt 306 b.Additionally, drive mechanism 230 may include additional components toassist in maintaining the engagement, such as with a magnetic couplingbetween starter piece 292 and drive mechanism 294. As can be furtherappreciated, while illustrated with a drive belt 306 b, drive mechanism294 a may alternatively incorporate different features for engaging thebottom surfaces of starter piece 292, support structure 252, andscaffold 254 (e.g., drive wheels).

As shown in FIG. 9, as drive mechanism 294 continues to index scaffold254 in the direction of arrow 286, the successive layers of 3D part 250and scaffold 254 pass through the thermal gradient at port 258 and moveoutside of chamber 234. In this embodiment, the table or surface 232desirably steps up outside of chamber walls 248 to receive alignmenttabs 312, 316, and 318, allowing them to slide across table 232 duringthe indexing. Furthermore, the stepped-up portion of table 232 may betreated or polished, may include low-friction material(s) (e.g.,polytetrafluoroethylene), and/or may include air jets to form a cushionof air, thereby reducing the sliding friction with alignment tabs 312,316, and 318. Alternatively, in embodiments in which alignment tabs 312,316, and 318 are omitted, the stepped-up portion of table 232 may beflush with or slightly below the elevation of guide rails 308 to receiveconveyor base 288 of scaffold 254.

Upon passing through port 258, the printed layers may then cool down tothe ambient temperature outside of chamber 234 (e.g., room temperature).The printing operation may continue until the last layer of 3D part 250is printed. As can be appreciated, by printing support structure 252 andscaffold 254 with edge segments 314 and 318 that are engagable by drivemechanism 294, system 230 effectively grows its own conveyor mechanism.The use of a conveyor-base scaffold in this manner allows guide rails308 to be relatively short, and even remain within chamber walls 248.This reduces the overall size of system 230, and effectively allows 3Dpart 250 to be printed with an unbound length along the z-axis.

FIGS. 10-14 show system 430, which is a third example additivemanufacturing system having a wedge starter piece and associated drivemechanism. As shown in FIG. 10, system 430 may operate in a similarmanner to system 230 (shown in FIGS. 6-9), where the reference numbersfor the respective features are increased by “400” from those of system30 (shown in FIGS. 2-5) and by “200” from those of system 230. In thisembodiment, the platen starter piece 292 of system 230 is replaced witha wedge starter piece 492.

Starter piece 492 is a print foundation that is similar to starter piece292, and includes wedge portion 496 (in lieu of platen portion 296) andplatform portion 498. Wedge portion 496 has a sloped geometry thatincludes receiving surface 496 a for receiving the printed layers ofsupport structure 452. Platform portion 498 includes edge segments 502and central segment 504, and functions in the same manner as platformportion 298 of start piece 292. Wedge portion 296 is integrally formedwith or otherwise connected to platform portion 298 at central segment504, and does not extend laterally to edge segments 502. As such,receiving surface 496 a extends parallel to the x-y plane, and at aright angle to platform portion 498, which extends in the y-z plane.

Starter piece 292 (shown in FIGS. 6-9) and starter piece 492 illustrateexample starter pieces of the present disclosure. Each starter piece ofthe present disclosure may include a platform portion and a receivingsurface, where the particular geometry for structurally reinforcing thereceiving surface relative to the platform portion may vary. Inembodiments in which the receiving surface is small, no additionalstructural reinforcement is necessary, and the starter piece may have an“L”-shaped or block-shaped geometry. As the size of the receivingsurface increases, one or more structural reinforcements (e.g.,reinforcing arms 300 and the sloped geometry of wedge portion 496) maybe desired to prevent the receiving surface from flexing or wobblingduring printing operations.

As shown in FIGS. 10 and 11, drive mechanism 494 is a wheel-based drivemechanism that functions in the same manner as drive mechanism 294, andincludes two pairs of drive wheels 506, guide rails 508, and motor 510,where, in FIG. 7, guide rails 308 are illustrated with cross hatching(and head gantry 242 is omitted) for ease of viewability. Prior to theprinting operation, platform portion 498 of starter piece 492 may beinserted between the pairs of drive wheels 506. Print head 440 may theninitially print one or more layers of support structure 452 ontoreceiving surface 496 a, where the sloped geometry of wedge portion 496reinforces receiving surface 496 a.

However, as shown in FIG. 12, receiving surface 496 a of wedge portion496 has a small cross-sectional area compared to receiving surfaces 36 aand 296 a, and is also smaller than the combined footprint areas of 3Dpart 450 and scaffold 454. As such, in this embodiment, supportstructure 452 may grow with an increasing cross-sectional area in thex-y plane. This may be accomplished by printing the successive layers ofsupport structure 452 with increasing cross-sectional areas in the x-yplane. For example, the successive layers of support structure 452 maybe printed with an angle of increasing size (e.g., angle 526) up toabout 45 degrees in any direction from the z-axis without requiringsupport from the previous layers.

Support structure 452 may grow with an increasing cross-sectional areaat least until it encompasses the footprint area of 3D part 450 andscaffold 454 (i.e., the cross-sectional area of 3D part 450 and scaffold454 in the x-y build plane). Additionally, as best shown in FIGS. 13Aand 13B, the layers of support structure 452 may be printed to includeedge segments 514 corresponding to edge segments 502 of starter piece492, and alignment tabs 516 (shown in FIG. 13B) corresponding toalignment tabs 512 of starter piece 492.

After each layer of support structure 452 is printed, drive mechanism494 may index starter piece 492 along the z-axis in the direction ofarrow 286 by a single layer increment in the same manner as discussedabove for starter piece 292 and drive mechanism 294. Thus, the lastprinted layer of support structure 452 functions as a print foundationreceiving surface for 3D part 450 and scaffold 454. Print head 440 maythen print layers of 3D part 450 and scaffold 454, and optionally anyadditional layers of support structure 452. As further shown in FIGS.13A and 13B, conveyor base 488 of scaffold 454 is printed to includeedge segments 518 corresponding to edge segments 502 and 514, andalignment tabs 520 corresponding to alignment tabs 512 and 516.

As drive wheels 506 continue to index starter piece 492 in the directionof arrow 486, alignment tabs 516 of support structure 452 and alignmenttabs 520 of scaffold 454 eventually reach and slidably couple with guiderails 508 to maintain proper registration in the x-y plane. Furthermore,as illustrated by arrow 522 in FIG. 13A, drive wheels 506 eventuallypass edge segments 502 of starter piece 492, and engage edge segments514 and 518 to continue to index support structure 450 and scaffold 454in the direction of arrow 486.

As shown in FIG. 14, as drive mechanism 494 continues to index scaffold454 in the direction of arrow 486, the successive layers of 3D part 450and scaffold 454 to pass through the thermal gradient at port 458 andmove outside of chamber 434. Upon passing through port 458, the printedlayers may then cool down to the ambient temperature outside of chamber434 (e.g., room temperature).

The printing operation may continue until the last layer of 3D part 450is printed, or, as discussed below, additional 3D parts may be printedwith the use of scaffold 454, where portions of scaffold 454 mayfunction as print foundation receiving surfaces for the additional 3Dparts. The use of starter piece 492 achieves the same benefits as theuse of starter piece 292 by reducing the overall size of system 430, andallowing 3D part 450 to be printed with an unbound length along thez-axis. In addition, wedge portion 496 reduces the size and weight ofstarter piece 492 relative to starter piece 292, and allows the lastlayer of support structure 452 to function as a print foundationreceiving surface for 3D part 450 and scaffold 454.

Vertical Printing

FIGS. 15 and 16 illustrate system 630, which is an example additivemanufacturing system of the present disclosure having an extendedprinting volume for printing tall 3D parts vertically, such as discussedabove for 3D part 10 (shown in FIG. 1A). As shown in FIG. 15, system 630may operate in a similar manner to system 430 (shown in FIGS. 10-14),where the reference numbers for the respective features are increased by“600” from those of system 30 (shown in FIGS. 2-5), by “400” from thoseof system 230 (shown in FIGS. 6-9), and by “200” from those of system430.

In the shown embodiment, system 630 may be supported on legs or othersuitable extensions 730 above a floor or other suitable surface 632.Port 658 extends through a bottom chamber wall 648 and is substantiallyparallel to the x-y plane. Accordingly, system 630 is configured toprint 3D part 650, support structure 652, and scaffold 654 along aprinting z-axis that is a vertical axis, where starter piece 692 may beindexed downward along the z-axis in the direction of arrow 686.

As drive mechanism 694 continues to index starter piece 692, supportstructure 652, and scaffold 654 downward in the direction of arrow 686,the successive layers of 3D part 650, support structure 652, andscaffold 654 pass through the thermal gradient at port 658, and moveoutside of chamber 634. Upon passing through port 658, the printedlayers may then cool down to the ambient temperature outside of chamber634 (e.g., room temperature). The printing operation may continue untilthe last layer of 3D part 650 is printed, or and/or when starter piece692 is fully indexed to surface 632. As can appreciated, allowing 3Dpart 650 to move downward out of chamber 634 increases the height thatmay be printed by system 630 compared to additive manufacturing systemshaving enclosed chambers.

As discussed above for scaffolds 18 a and 18 b (shown in FIG. 1A),scaffold 654 may be printed to brace the lateral sides of 3D part 650.As shown in FIG. 16, this allows drive mechanism 694 to index scaffold654 downward. Additionally, scaffold 654 may reduce or prevent wobblingthat may occur while 3D part 650 is printed, thereby substantiallymaintaining proper registration between 3D part 650 and print head 640.

While described with a wedge starter piece 692 and wheel-based drivemechanism 694, system 630 may alternatively be used with a variety ofdifferent print foundations and drive mechanisms, such as a platen andplaten gantry (e.g., platen 36 and platen gantry 38) and a platenstarter piece (e.g., starter piece 292), which may be used in the samemanners as discussed above for systems 30 and 230. In these embodiments,scaffold 654 may continue to be used to reduce wobbling by laterallybracing 3D part 650.

Multiple Chambers

The above-discussed embodiments for the additive manufacturing systemsof the present disclosure may be referred to as single-chamber systemsthat provide two temperature zones (i.e., inside the chamber and theambient conditions outside the chamber). FIG. 17 illustrates analternative system 830 having multiple chambers to provide fourtemperatures zones. As shown in FIG. 17, system 830 may operate in asimilar manner to system 430 (shown in FIGS. 10-14), where the referencenumbers for the respective features are increased by “800” from those ofsystem 30 (shown in FIGS. 2-5), by “600” from those of system 230 (shownin FIGS. 6-9), by “400” from those of system 430, and by “200” fromthose of system 630.

System 830 includes chambers 834 a, 834 b, and 834 c, respectivelyhaving chamber walls 848 a, 848 b, and 848 c, heating mechanisms 856 a,856 b, and 856 c, and ports 858 a, 858 b, and 858 c. Themultiple-chamber arrangement provides multiple temperature gradients atports 858 a, 858 b, and 858 c. For example, heating mechanism 856 a maymaintain chamber 834 a at a first temperature(s), heating mechanism 856b may maintain chamber 834 b at a second temperature(s) lower than thefirst temperature(s), and heating mechanism 856 c may maintain chamber834 c at a third temperature(s) lower than the second temperature(s) andhigher than the ambient conditions (e.g., room temperature).

This embodiment is particularly suitable for use with materials that aretemperature and oxygen sensitive, such as polyamide materials (e.g.,nylon-based materials), which can oxidize when exposed to elevatedtemperatures in a heated environment, potentially rendering thembrittle. As discussed above for the single-chamber systems 30, 230, 430,and 630, the drive mechanisms desirably index the print foundations atrates that are slow enough such that the printed layers reside in thechamber for a duration that is sufficient to substantially relievecooling stresses, prior to reaching the port to ambient conditions. Thisallows the printed layers to be relaxed enough such that when they reachthe temperature gradient at the port, the temperature drop at thetemperature gradient does not cause any substantial distortions orcurling. However, this can cause temperature/oxygen-sensitive materialsto oxidize prior to reaching the port.

Instead, as shown in FIG. 17, the use of multiple chambers allows theprinted layers to exit chamber 834 a into chamber 834 b via port 858 aprior to fully relieving their cooling stresses. The secondtemperature(s) of chamber 834 b are desirably high enough to allow thelayers to gradually relax without distorting or curling, while also lowenough to reduce the rate of oxidation for the part material (or preventoxidation entirely). This process may continue into chamber 834 c (viaport 858 b) as well to continue to gradually relax the printed layersprior reaching port 858 c.

The particular temperatures maintained in chambers 834 a, 834 b, and 834c may vary depending on the particular part and support materials used.Furthermore, the number of chambers (chambers 834 a, 834 b, and 834 cmay vary). Suitable numbers of chamber range from one to five.Additionally, the dimensions of each chamber may be the same ordifferent to accommodate the cooling of different part and supportmaterials. In some embodiments, the dimensions of each chamber may bechangeably, such as with accordion-style walls 848 a, 848 b, and 848 cto further accommodate the cooling of different part and supportmaterials. As can be appreciated, the use of multiple, successivechambers maintained at step-down temperatures increases the number ofmaterials that may be printed with the additive manufacturing systems ofthe present disclosure.

Scaffolds

As discussed above, the scaffolds of the present disclosure (e.g.,scaffolds 54, 254, 454, and 654) may provide multiple functions duringprinting operations with additive manufacturing systems. For example,the scaffolds may laterally brace the printed 3D parts during horizontalprinting operations to prevent the 3D parts from sagging due to gravity.Alternatively, the scaffolds may laterally brace the printed 3D partsduring vertical printing operations to prevent the 3D parts fromwobbling. Furthermore, during both horizontal and vertical printingoperations, the scaffolds may include conveyor bases that are indexableby drive mechanisms of the additive manufacturing systems, therebyallowing the 3D parts and scaffolds to be indexed outside of thesystems, without requiring long gantries. Additionally, as discussedbelow, the scaffolds may function as print foundation receiving surfacesfor printing multiple, successive 3D parts.

FIGS. 18A-18C and 19 illustrate example scaffolds that may be printedwith additive manufacturing systems. However, the scaffolds of thepresent disclosure are not limited to these particular embodiments andmay alternatively include a variety of different geometries depending ontheir particular purposes. Nonetheless, the embodied scaffolds shown inFIGS. 18 and 19 are particularly suitable for use when printing 3D partsthat are long or tall along their printing axes relative to theircross-sectional dimensions.

In the examples shown in FIGS. 18A-18C and 19, the scaffolds are printedwith thin-walled 3D parts (e.g., thin-walled panels). In someembodiments, each layer of a thin-walled 3D part, support structure,and/or scaffold may be printed with narrow perimeter roads and a widerinterior road with the use of a print head nozzle as disclosed inco-filed U.S. patent application Ser. No. ______, entitled “Print HeadNozzle For Use With Additive Manufacturing System” (attorney docket no.S697.12-0231). Additionally, the 3D parts, support structures, andscaffolds disclosed herein may be printed with draw control techniquesas disclosed in co-filed U.S. patent application Ser. No. ______,entitled “Draw Control For Additive Manufacturing Systems” (attorneydocket no. S697.12-0233).

For example, FIG. 18A illustrates thin-walled 3D part 940 printedhorizontally with scaffold 942, which may be performed in the samemanner as discussed above for scaffolds 54, 254, and 454. In thisexample, 3D part 940 includes major exterior surfaces 940 a and 940 b,and scaffold 942 includes ribbon portion 944 and conveyor base 946.Ribbon portion 944 braces exterior surface 940 b of 3D part 940 againstgravity with contact points 948.

Contact points 948 are located intermittently along the z-axis (notshown) at each wave peak of ribbon portion 944, and each may be a singledrop of part or support material that connects exterior surface 940 b toribbon portion 944. In particular, contact points 948 may be attangential locations of the wave pattern of ribbon portion 944. Thecollection of contact points 948 allow ribbon portion 944 to laterallybrace 3D part 940 against gravity (i.e., to prevent sagging), while alsoallowing ribbon portion 944 to be readily removed from 3D part 940without undue effort.

In embodiments in which the droplets at contact points 948 are derivedfrom the part material, the droplets may function as break-awaylocations due to their relatively weak bonds. Alternatively, inembodiments in which the droplets at contact points 948 are derived froma soluble support material, the droplets may be dissolved away toseparate ribbon portion 944 from 3D part 940. Conveyor base 946 is aplanar sheet that supports ribbon portion 944, providing a smoothsurface that can rest on and slide over guide rails and/or othersurfaces, and may also assist in indexing scaffold 942 and 3D part 940,as discussed above.

Alternatively, as shown in FIG. 8B, a single scaffold 942 may laterallybrace multiple adjacently-printed parts 940 a and 940 b. In thisembodiment, 3D parts 940 a and 940 b may be printed laterally adjacentto each other along the y-axis, where ribbon portion 944 stabilizes eachof them.

Additionally, as shown in FIG. 18C, multiple scaffolds 942 a and 942 b(having ribbon portions 944 a and 944 b) may be used to print multiple,stacked 3D parts 940 a and 940 b that are adjacent to each other alongthe x-axis. In this embodiment, ribbon portion 944 b (or multipleribbons 944 b) may be disposed between the stacked 3D parts 940 a and940 b to brace them against sagging while printing along the horizontalz-axis.

FIG. 19 illustrates thin-walled 3D part 950 printed vertically withscaffold 952, which may be performed in the same manner as discussedabove for scaffold 654, or may be printed vertically in an additivemanufacturing system having a large enclosed chamber, such as anadditive manufacturing system commercially available from Stratasys,Inc., Eden Prairie, Minn. under the trademarks “FDM” and “FORTUS 900mc”.In this example, 3D part 950 includes major exterior surfaces 950 a and950 b, and scaffold 952 only includes ribbon portion 954 (no conveyorbase), which braces exterior surface 950 b of 3D part 940 againstwobbling with contact points 956. Contact points 956 may function in thesame manner as contact points 948 for bracing 3D part 950 during theprinting operation, while also allowing scaffold 952 to be readilyremoved from 3D part 950 after the printing operation is completed. Forexample, contact points 956 may be at tangential locations of the wavepattern of ribbon portion 954.

However, as discussed above, in the vertical printing orientation,scaffold 952 functions as a lateral brace to reduce or prevent 3D part250 from wobbling during the printing operation. For example, when 3Dpart 950 and scaffold 952 are printed with system 630 (shown in FIGS. 15and 16), scaffold 952 may laterally brace 3D part 950 as platen 636indexes downward out of chamber 634. Alternatively, when printing in alarge enclosed chamber, such as in an additive manufacturing systemcommercially available from Stratasys, Inc., Eden Prairie, Minn. underthe trademarks “FDM” and “FORTUS 900mc”, scaffold 952 may laterallybrace 3D part 950 as the platen indexes downward within the largeenclosed chamber. In each of these situations, scaffold 950 may reduceor prevent 3D part 950 from wobbling, thereby substantially maintainingproper registration between 3D part 950 and the print head.

This is particularly suitable for a 3D part having an aspect ratio ofthe height along the printing z-axis relative to its smallestcross-sectional area in the x-y plane (or the plane perpendicular to theprint axis) that is about 5:1 or greater. Thus, the scaffold (e.g.,scaffold 950) desirably has a cross-sectional area in the x-y plane (orthe plane perpendicular to the print axis) such that a combinedcross-sectional area for each printed layer (of the 3D part andscaffold) is less than 5:1.

Furthermore, scaffolds 942 and 952 may be printed with single roadwidths per layer. For example, each layer of ribbon portion 944 andconveyor base 946 of scaffold 942 (shown in FIG. 17) may each be printedwith a single road width, and each layer of ribbon portion 954 ofscaffold 952 (shown in FIG. 18) may be printed with a single road width.

The wave patterns of ribbon portions 944 and 954 allow the print head toprint each layer at a substantially constant tip speed or velocitywithout having to slow down at corner vertices at the crests and valleysof the waves. This, along with the single-road width, can substantiallyreduce printing times. Furthermore, the wave patterns of ribbon portions944 and 954 allow a substantially constant draw to be maintained, asdisclosed in co-filed U.S. patent application Ser. No. ______, entitled“Draw Control For Additive Manufacturing Systems” (attorney docket no.S697.12-0233), which provides good, smooth roads with reduced or norippling or cresting.

The scaffolds of the present disclosure are also suitable for printingmultiple, successive 3D parts in a continuous manner, particularly whenused in combination with the additive manufacturing systems and starterpieces of the present disclosure. FIG. 20A shows 3D parts 958 a, 958 b,and 958 c respectively printed on support structures 960 a, 960 b, and960 c, with the use of scaffold assembly 962 (having scaffold segments962 a, 962 b, and 962 c), and starter piece 964, while being indexed inthe direction of arrow 966. 3D part 958 a, support structure 960 a, andthe ribbon-base portion of scaffold segment 962 a may be printed onstarter piece 964 in the same manner as discussed above for 3D part 450,support structure 452, scaffold 454, and starter piece 492 (shown inFIGS. 6-9).

However, if multiple 3D parts are in queue for successive printing, thesystem (e.g., system 430) may continue to print scaffold segment 962 ato generate wedge portion 968 having an increasing cross-sectional area(in the same manner as discussed above for support structure 452). Assuch, the layers of wedge portion 968 of scaffold segment 962 a may beprinted with increasing cross-sectional areas until they at leastencompass the footprint area of 3D part 958 b and scaffold segment 962b. Thus, the last layer of wedge portion 968 functions as a printfoundation receiving surface for support structure 960 b. At this point,support structure 960 b, 3D part 958 b, and scaffold segment 962 b maybe printed, where support structure 960 b is disposed between scaffoldsegment 962 a and 3D part 958 b. Printing support structure 960 bbetween wedge portion 968 and 3D part 958 b allows 3D part 958 b to besubsequently separated from scaffold 962 b (e.g., by dissolving supportstructure 960 b), and may reduce curling effects on 3D part 958 b.

The same technique may then be repeated to print wedge portion 970 ofscaffold segment 962 b, and then to print support structure 960 c, 3Dpart 958 c, and scaffold segment 962 b. With the systems of the presentdisclosure having ported heated chambers, this process may continue aslong as desired to continuously print successive 3D parts. Each scaffoldwedge portion (e.g., wedge portions 968 and 970) may have differentdimensions corresponding to the footprint areas of their respective 3Dparts, where each wedge portion defines a planar receiving surface inthe x-y plane for starting the subsequent printing. Thus, each printed3D part may have different dimensions and geometries.

In the shown example, wedge portion 968 and 970 are printed ascomponents of scaffold segments 962 a and 962 b. In alternativeembodiments, wedge portion 968 and 970 may be printed as components ofsupport structures 960 b and 960 c in the same manner as supportstructure 960 a. In these embodiments, the layers of support structures960 b and 960 c may be printed with increasing cross-sectional areas, asdiscussed above for support structure 452 (as best shown above in FIG.12).

Furthermore, as shown in FIG. 20B, support structure 960 b may cover theentire footprint area of 3D part 958 b and scaffold segment 962 b,providing an edge segment for support structure 960 b. Similarly,support structure 960 c may cover the entire footprint area of 3D part958 c and scaffold segment 962 c, providing an edge segment for supportstructure 960 c. In this embodiment, scaffold segments 962 a, 962 b, and962 c may be entirely separate scaffolds that are separated by supportstructures 960 b and 960 c.

3D parts may be printed with this continuous technique by providing toolpath and related print instructions to the additive manufacturing systemfor each 3D part, support structure, and scaffold. In one embodiment, ahost computer (e.g., host computer 484) may receive digitalrepresentations of each 3D part to be printed successively. The hostcomputer may initially slice each digital 3D part and render theassociated tool paths. The host computer can also generate tool pathsfor the support structures and scaffolds, where the support structuresand/or scaffolds have the wedge portions to receive the successive 3Dparts.

For example, the host computer may initially determine or otherwiseidentify the cross-sectional area of the print foundation receivingsurface (e.g., the receiving surface for starter piece 964) and thecombined footprint area of 3D part 958 a and scaffold 962 a. The hostcomputer may then generate tool paths for the layers of supportstructure 960 a, where the layers have increasing cross-sectional areas,starting at the location of the print foundation receiving surface,until they encompass the combined footprint area of 3D part 658 a andscaffold 962 a. The host computer may also slice the digitalrepresentation of the 3D part 958 a, render the associated tool pathsfor each layer, and generate tool paths of the layers for scaffold 962a.

For 3D part 958 b, the host computer may determine or otherwise identifythe cross-sectional area of the last layer of scaffold 962 a (prior towedge portion 968) and the combined footprint area of 3D part 958 b andscaffold 962 b. The host computer may then generate tool paths for thelayers of wedge portion 968, where the layers have increasingcross-sectional areas, starting at the location of the last layer ofscaffold 962 a, until they encompass the combined footprint area of 3Dpart 658 b and scaffold 962 b. The host computer may also slice thedigital representation of the 3D part 958 b, render the associated toolpaths for each layer, generate tool paths of the layers for supportstructure 960 b, and generate tool paths of the layers for scaffold 962a. As discussed above, the tool paths for the layers of wedge portion968 may alternatively be generated as part of support structure 960 b.

The same process may then be repeated for wedge portion 970, 3D part 958c, support structure 960 c, and scaffold 962 c; and for each subsequent3D part thereafter. The host computer may then transmit the generatedtool paths and related printing information to the additivemanufacturing system to print the 3D parts, support structures, andscaffolds.

In an alternative embodiment, the host computer may receive digitalrepresentations of the 3D parts in a piecemeal manner. For example, thehost computer may receive, slice, and generate tool paths for 3D parts958 a and 958 b, support structures 960 a and 960 b, and scaffoldsegments 962 a and 962 b. Since, in this example, there are no intended3D parts to be printed after 3D part 958 b, only the ribbon-base portionof scaffold segment 962 b is needed (i.e., wedge portion 970 is notgenerated). The host computer may then transmit the generated tool pathsand related printing information to the additive manufacturing system toprint 3D parts 958 a and 958 b, support structures 960 a and 960 b, andscaffold segments 962 a and 962 b (without wedge portion 970).

If, while the additive manufacturing system is printing, the hostcomputer then receives a digital representation of 3D part 958 c, thehost computer may then slice and generate tool paths for 3D part 958 c,support structure 960 c, wedge portion 970 of scaffold segment 962 b,and scaffold segment 962 c. The host computer may then transmit thegenerated tool paths and related printing information to the additivemanufacturing system to add to the end of its previous printinginstructions. This is attainable because the cross-sectional area of thelast layer of scaffold segment 962 b is known, allowing wedge portion970 to be printed with an increasing cross-sectional area from the lastlayer of scaffold segment 962 b.

This technique effectively allows the additive manufacturing system tocontinuously print multiple, successive 3D parts along a single scaffoldassembly, where each printed 3D part exits the chamber of the systemthrough its port (e.g., port 458). As can be appreciated, the use of astarter-piece print foundation and an associated drive mechanism, incombination with this technique, effectively allows an unlimited numberof 3D parts to be printed along the z-axis. After exiting the system, ifdesired, each printed 3D part may be separated from the growing scaffoldassembly at its support structure connection, and then removed from itsassociated scaffold, as discussed above.

EXAMPLES

The present disclosure is more particularly described in the followingexamples that are intended as illustrations only, since numerousmodifications and variations within the scope of the present disclosurewill be apparent to those skilled in the art.

Example 1

Horizontal printing operations were performed with an additivemanufacturing system commercially available from Stratasys, Inc., EdenPrairie, Minn. under the trademarks “FDM” and “UPRINT”, which wasoriented such that the printing z-axis was horizontal. A port was cutinto the base of the system, and a platen gantry was installed to thesystem such that the platen gantry extended out of the port for severalfeet. This system corresponded to system 30 (shown in FIGS. 2-5) havingan extended platen gantry.

The system was operated to print multiple long 3D parts, includingairfoils, manifolds, and thin-walled panels. During each printingoperation, the chamber of the system was initially heated to an elevatedoperating temperature. This created a thermal gradient at the portbetween the elevated operating temperature within the chamber and theambient air outside the chamber (about 25° C.).

The print head initially printed multiple layers of a support structureon a platen from a support material, which functioned as an adhesivebase for the subsequent printing. The print head then printed layers ofthe 3D part with a scaffold corresponding to scaffold 54, both from thesame part material. The scaffold had a ribbon portion and a conveyorbase, where the ribbon portion was connected to the 3D part withconnection point droplets of the part material (as discussed above forscaffold 942, shown in FIG. 18A).

After each layer was printed, the platen gantry indexed the platen by asingle layer increment, which allowed the 3D part and scaffold to growhorizontally. As this continued, the platen, the support structure, the3D part, and the scaffold eventually passed through the thermal gradientat the port to extend outside of the system. The base portion of thescaffold was properly supported by the guide rails of the platen gantry,allowing the scaffold to slide across the guide rails during eachindexing step.

When the printing operation was completed (after the 3D part andscaffold grew for several feet), the platen was removed from the platengantry, and broken away from the support structure. The supportstructure was then removed, and the scaffold was readily broken off fromthe 3D part. FIG. 21 is a photograph illustrating one of the printed 3Dparts and associated scaffold while still residing in thehorizontally-oriented system. The top opening through which thephotograph was taken was closed off during the printing operation, suchthat only a single port located behind the platen was open to theambient environment. The photograph was taken prior to completion of the3D part, showing only a small portion of the total length of the 3D partand scaffold.

Upon visual inspection, each 3D part printed in this manner exhibitedgood dimensional integrity due to the heated environment within thechamber, as well as use of the associated scaffold. The heatedenvironment within the chamber allowed the 3D parts and scaffolds tocool down slowly to be sufficiently solidified by the time they reachedthe thermal gradient at the port to prevent distortions or curling.Additionally, without the use of the scaffolds, the long 3D parts wouldhave otherwise sagged due to gravity during the printing operations. Thescaffolds, however, stabilized the layers of the 3D parts, allowing thelong 3D parts to be printed along the horizontal printing axis.

Example 2

Horizontal printing operations were also performed with the system ofExample 1, where the platen and platen gantry were replaced with a wedgestarter piece and associated drive mechanism. This system correspondedto system 430 (shown in FIGS. 10-14), and was operated to print multiplelong 3D parts. During each printing operation, the chamber of the systemwas initially heated to an elevated operating temperature. This createda thermal gradient at the port between the elevated operatingtemperature within the chamber and the ambient air outside the chamber(about 25° C.).

The print head initially printed multiple layers of a support structureon a receiving surface of a wedge portion of the starter piece. Asdiscussed above for the wedge starter piece 492, the layers of thesupport structure were printed with increasing cross-sectional area inthe vertical x-y plane. In particular, each successive layer was printedto provide an angle of increasing size (corresponding to angle 526,shown in FIG. 12) of about 45 degrees from the printing axis. This wascontinued until the footprint cross-sectional area of the intended 3Dpart and scaffold was reached.

The print head then printed layers of the given 3D part with a scaffoldcorresponding to scaffold 454, both from the same part material. Thescaffold had a ribbon portion and a conveyor base, where the ribbonportion was connected to the 3D part with connection point droplets ofthe part material (as discussed above for scaffold 942, shown in FIG.18A).

After each layer was printed, the drive mechanism indexed the wedgestarter piece by a single layer increment, which allowed the 3D part andscaffold to grow horizontally. As this continued, the wedge starterpiece, the support structure, the 3D part, and the scaffold eventuallypassed through the thermal gradient at the port to extend outside of thesystem. By this point, the drive mechanism had passed the wedge starterpiece and had engaged the edge segments of the conveyor base of thescaffold for the indexing steps.

When the printing operation was completed, the scaffold was removed fromthe drive mechanism. The wedge starter piece was then broken away fromthe support structure. The support structure was then dissolved away,and the scaffold was readily broken off from the 3D part. Upon visualinspection, each 3D part printed in this manner also exhibited gooddimensional integrity due to the heated environment within the chamber,as well as use of the associated scaffold. Furthermore, the scaffoldeffectively functioned as an indexing conveyor for the drive mechanism,allowing the overall footprint of the system to be reduced from that ofthe system in Example 1, and also effectively allowed the 3D parts to begrown to unbound lengths.

Example 3

A vertical printing operation was performed to produce a scaled-down carhood with a scaffold (corresponding to 3D part 950 and scaffold 952,shown in FIG. 19) using an additive manufacturing system commerciallyavailable from Stratasys, Inc., Eden Prairie, Minn. under the trademarks“FDM” and “FORTUS 900mc”. In this example, the system had a largeenclosed chamber used to print the scaled-down car hood and thescaffold.

The hood and the scaffold were each printed from a polycarbonatematerial with a print head nozzle as disclosed in co-filed U.S. patentapplication Ser. No. ______, entitled “Print Head Nozzle For Use WithAdditive Manufacturing System” (attorney docket no. S697.12-0231). Thescaffold was connected to the rear side of the hood with connectionpoint droplets of the part material at tangential locations of theribbon portion (as discussed above for scaffold 952). Each layer of theprinted hood was printed with a 120-mil wall thickness, which includedtwo 20-mil wide perimeter roads followed by an 80-mil wide internal fillroad. Each layer of the scaffold was printed as a 40-mil single-roadwall.

The resulting hood and scaffold are shown in FIGS. 22 and 23, where thehood was 35 inches wide and 27 inches tall. Upon visual inspection, theresulting hood exhibited good dimensional integrity due to the use ofthe scaffold, which laterally supported the hood during the printingoperation. This prevented the upper portion of the hood from wobblingduring the printing operation, thereby maintaining proper registrationbetween the print head and the layers of the hood.

Additionally, as described in co-filed U.S. patent application Ser. No.______, entitled “Print Head Nozzle For Use With Additive ManufacturingSystem” (attorney docket no. S697.12-0231), the additive manufacturingsystem with the above-mentioned nozzle printed the entire hood andscaffold in 24 hours and 25 minutes. In comparison, a standard printingoperation with a conventional nozzle suitable for printing 20-mil wideroads, requires about 76 hours to print the shown hood. As such, theprinting time was reduced by more than a factor of three.

Although the present disclosure has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the disclosure.

1. A method for printing three-dimensional parts with an additivemanufacturing system, the method comprising: printing successive layersalong a printing axis onto a first receiving surface of a printfoundation, wherein the printed successive layers have increasingcross-sectional areas parallel to a build plane that is normal to theprinting axis, wherein a last layer of the printed successive layersdefines a second receiving surface; and printing layers of athree-dimensional part onto the second receiving surface, wherein thelast layer of the printed successive layers has a first cross-sectionalarea parallel to the build plane, wherein a first layer defines of thethree-dimensional part has a second cross-sectional area parallel to thebuild plane, and wherein the first cross-sectional area is at least aslarge as the second cross-sectional area.
 2. The method of claim 1,wherein the printed successive layers define a soluble supportstructure.
 3. The method of claim 1, and further comprising printinglayers of a scaffold for the three-dimensional object onto the secondreceiving surface, wherein a first layer of the scaffold has a thirdcross-sectional area parallel to the build plane, and wherein the firstcross-sectional area is at least as large as a combination of the secondcross-sectional area and the third cross-sectional area.
 4. The methodof claim 3, wherein a last layer of the scaffold defines a thirdreceiving surface, and wherein the method further comprises printingsuccessive layers along the printing axis onto the third receivingsurface, wherein the successive layers printed onto the third receivingsurface have increasing cross-sectional areas parallel to the buildplane.
 5. The method of claim 4, wherein a last layer of the successivelayers printed onto the third receiving surface defines a fourthreceiving surface, and wherein the method further comprises printinglayers of a second three-dimensional part onto the fourth receivingsurface.
 6. The method of claim 4, wherein the successive layers printedonto the third receiving surface are printed as a wedge portion of thescaffold, and wherein the method further comprises printing a supportstructure onto the fourth receiving surface, and wherein printing thelayers of a second three-dimensional part onto the fourth receivingsurface comprise printing the layers onto the support structure.
 7. Themethod of claim 1, wherein the print foundation includes a starter piececomprising: a first portion having the first receiving surface; and aplatform portion having edge segments on opposing sides of the firstportion.
 8. The method of claim 7, and further comprising engaging theedge segments of the platform portion with a drive mechanism of theadditive manufacturing system to index the starter piece along theprinting axis.
 9. A method for printing three-dimensional parts with anadditive manufacturing system, the method comprising: providing a firstcross-sectional area of a receiving surface parallel to a build plane;providing a footprint area of a three-dimensional part parallel to thebuild plane; generating tool paths for successive layers that increasein cross-sectional areas parallel to the build plane from the firstcross-sectional area to at least the footprint area of thethree-dimensional part; printing the successive layers with the additivemanufacturing system onto the receive surface based on the generatedtool paths; and printing a three-dimensional part onto the printedsuccessive layers.
 10. The method of claim 9, wherein the printedsuccessive layers define a support structure.
 11. The method of claim 9,wherein the printed successive layers define a wedge portion of ascaffold.
 12. The method of claim 11, and further comprising printing asupport structure onto the printed successive layers, wherein printingthe three-dimensional part onto the printed successive layers comprisesprinting the three-dimensional part onto the support structure.
 13. Themethod of claim 9, and further comprising: providing a footprint area ofa scaffold parallel to the build plane; generating tool paths forsuccessive layers that increase in cross-sectional areas parallel to thebuild plane from the first cross-sectional area to at least a combinedarea of the footprint areas of the three-dimensional part and thescaffold; and printing the scaffold onto the printed successive layers,wherein the scaffold braces the three-dimensional part parallel to thebuild plane.
 14. The method of claim 9, wherein the receiving surface isa surface of a print foundation retained by the additive manufacturingsystem.
 15. A method for printing three-dimensional parts with anadditive manufacturing system, the method comprising: printing ascaffold along a printing axis with the additive manufacturing system,wherein the printed scaffold comprises a plurality of successive wedgeportions offset along the printing axis, and wherein each wedge portionhas a receiving surface with a cross-sectional area parallel to a buildplane that is normal to the printing axis; and printing athree-dimensional part onto each printed receiving surface, such thateach three-dimensional part is associated with one of the receivingsurfaces, wherein each three-dimensional part has a cross-sectional areaparallel to the build plane that is less than or equal to thecross-sectional area of its associated receiving surface.
 16. The methodof claim 15, and further comprising printing a support structure ontoeach receiving surface, wherein printing a three-dimensional part ontoeach printed receiving surface comprises printing each three-dimensionalpart onto one of the support structures.
 17. The method of claim 16,wherein each support structure comprises a soluble support material. 18.The method of claim 16, wherein each support structure separates thescaffold into separate scaffold segments, each scaffold segment havingat least one of the wedge portions.
 19. The method of claim 15, whereinthe printed scaffold comprises edge segments, and wherein the methodfurther comprises engaging the edge segments of the platform portionwith a drive mechanism of the additive manufacturing system to index thescaffold along the printing axis.
 20. The method of claim 15, wherein atleast two of the plurality of successive wedge portions have differentgeometries.